Uplink carrier configuration and selection with supplementary uplink

ABSTRACT

A user equipment (UE) is configured with at least one uplink carrier of a normal uplink carrier and a supplementary uplink carrier. The UE selects the supplementary uplink carrier if a measured RSRP is below a threshold. The UE performs a random access preamble transmission using a random access resources configured in association to the selected supplementary uplink carrier.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of and priority to U.S. ProvisionalApplication No. 62/616,397 filed on Jan. 11, 2018 and entitled “UPLINKCARRIER CONFIGURATION AND SELECTION WITH SUPPLEMENTARY UPLINK,”(hereinafter referred to as “US73080 application”). The disclosure ofthe US73080 application is hereby incorporated fully by reference intothe present disclosure.

FIELD

The present disclosure generally relates to a method for uplinkconfiguration and selection with supplementary uplink performed by auser equipment and user equipment performing the same.

BACKGROUND

In New Radio (NR), high frequency band is considered to be adopted toimprove transmission data rate, for example in enhanced Mobile BroadBand (eMBB) scenarios. However, the radio coverage of high frequencyband diminishes over distances. Especially on uplink, the transmissionpower is limited for a user equipment (UE). A supplementary uplink (SUL)carrier on a lower frequency band is introduced to compensate the highfrequency band uplink coverage and to improve signal quality near thecell edges.

SUMMARY

The present disclosure is directed to uplink configuration and selectionwith supplementary uplink for a user equipment and a related basestation.

In one aspect of the present disclosure, a user equipment (UE) forwireless communication is provided. The UE comprises one or morenon-transitory computer-readable media having computer-executableinstructions embodied thereon and at least one processor coupled to theone or more non-transitory computer-readable media. The at least oneprocessor is configured to execute the computer-executable instructionsto receive configuration information associated with at least two uplinkcarriers, to select one of the at least two uplink carriers if power ofa first downlink reference signal measured by the UE is below a firstthreshold value, to select a contention-free random access (CFRA)resource associated with a second downlink reference signal on theselected uplink carrier if power of the second downlink reference signalmeasured by the UE is above a second threshold value, wherein the seconddownlink reference signal is synchronization signal block (SSB) orchannel state information reference signal (CSI-RS), wherein the secondthreshold value is associated with signal quality of the SSB and theCFRA resource is associated with the SSB if the second downlinkreference signal is the SSB, and wherein the second threshold value isassociated with signal quality of the CSI-RS and the CFRA resource isassociated with the CSI-RS if the second downlink reference signal isthe CSI-RS, and to perform a random access procedure using the selectedCFRA resources and the selected uplink carrier.

In one aspect of the present disclosure, a method for wirelesscommunication, performed by a user equipment (UE), is provided. Themethod, performed by the UE, comprises receiving configurationinformation associated with at least two uplink carriers, selecting oneof the at least two uplink carriers if power of a first downlinkreference signal measured by the UE is below a first threshold value,selecting a contention-free random access (CFRA) resource associatedwith a second downlink reference signal on the selected uplink carrierif power of the second downlink reference signal measured by the UE isabove a second threshold value, wherein the second downlink referencesignal is synchronization signal block (SSB) or channel stateinformation reference signal (CSI-RS), wherein the second thresholdvalue is associated with signal quality of the SSB and the CFRA resourceis associated with the SSB if the second downlink reference signal isthe SSB, and wherein the second threshold value is associated withsignal quality of the CSI-RS and the CFRA resource is associated withthe CSI-RS if the second downlink reference signal is the CSI-RS, andperforming a random access procedure using the selected CFRA resourcesand the selected uplink carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the exemplary disclosure are best understood from thefollowing detailed description when read with the accompanying figures.Various features are not drawn to scale. Dimensions of various featuresmay be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic diagram illustrating a wireless communicationsystem configured with a normal uplink carrier and a supplementaryuplink carrier.

FIG. 2 is a schematic diagram illustrating a wireless communicationsystem according to one embodiment of the present disclosure.

FIGS. 3A and 3B are a schematic diagrams illustrating uplinkconfigurations for physical uplink control channel (PUCCH) according toone embodiment of the present disclosure.

FIG. 4 is a schematic information element structure according to oneembodiment of the present disclosure.

FIG. 5 is a schematic information element structure according to anotherembodiment of the present disclosure.

FIG. 6 is a decision flow chart for a UE to perform random accesspreamble transmission according to one embodiment of the presentdisclosure.

FIG. 7 is a decision flow chart for a UE to perform random accesspreamble transmission according to another embodiment of the presentdisclosure.

FIG. 8 is a block diagram of a device for wireless communication inaccordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION

The following description contains specific information pertaining toexemplary embodiments in the present disclosure. The drawings in thepresent disclosure and their accompanying detailed description aredirected to merely exemplary embodiments. However, the presentdisclosure is not limited to merely these exemplary embodiments. Othervariations and embodiments of the present disclosure will occur to thoseskilled in the art. Unless noted otherwise, like or correspondingelements among the figures may be indicated by like or correspondingreference numerals. Moreover, the drawings and illustrations in thepresent disclosure are generally not to scale, and are not intended tocorrespond to actual relative dimensions.

The description uses the phrases “in one embodiment,” “in oneimplementation,” “in some implementations,” or “in some embodiments,”which may each refer to one or more of the same or differentembodiments. The term “coupled” is defined as connected, whetherdirectly or indirectly through intervening components, and is notnecessarily limited to physical connections. The term “comprising,” whenutilized, means “including, but not necessarily limited to”; itspecifically indicates open-ended inclusion or membership in theso-described combination, group, series and the equivalent.

It is noted that the term “and/or” includes any and all combinations ofone or more of the associated listed items. It will also be understoodthat, although the terms first, second, third etc. may be used herein todescribe various elements, components, regions, parts and/or sections,these elements, components, regions, parts and/or sections should not belimited by these terms. These terms are only used to distinguish oneelement, component, region, part or section from another element,component, region, part or section. Thus, a first element, component,region, part or section discussed below could be termed a secondelement, component, region, part or section without departing from theteachings of the present disclosure.

It should be noted that, in the present disclosure, a UE may include,but is not limited to, a mobile station, a mobile terminal or device, auser communication radio terminal. For example, a UE may be a portableradio equipment, which includes, but is not limited to, a mobile phone,a tablet, a wearable device, a sensor, a personal digital assistant(PDA), or a television display with wireless communication capability.The UE is configured to receive and transmit signals over an airinterface to one or more cells in a radio access network.

A base station may include, but is not limited to a node B (NB) as in aUniversal Mobile Telecommunication System (UMTS), an evolved node B(eNB) as in Long-Term Evolution Advanced (LTE-A), a radio networkcontroller (RNC) as in the UMTS, a base station controller (BSC) as inGlobal System for Mobile Communication/GSM EDGE (Enhanced Data rate forGSM Evolution) Radio Access Network (GSM/GERAN), a next generation eNB(ng-eNB) as a node providing Evolved Universal Terrestrial Radio Access(E-UTRA) user plane and control plane protocol terminations towards theUE and connected via the NG interfaces to the 5G core network (5GC), anext generation node B (gNB) as in the 5G Access Network (5G-AN), andany other apparatus capable of controlling radio communication withcellular positioning technology and managing radio resources within acell. The base station may connect to serve the one or more UEs througha radio interface to the network. A base station, a cell, a gNB and agNB/cell may be used interchangeably hereinafter.

A UE in RRC_CONNECTED mode may measure a downlink (DL) signal qualitysent from a base station via, for example, broadcast signal, dedicatedcontrol signal and/or data stream signal. In some implementations, theUE may measure the DL signal periodically. The base station may sendrandom access resources/parameters (e.g., physical random access channelconfiguration), supplementary uplink (SUL) carrier configuration and/ornon-supplementary uplink (non-SUL) carrier configuration by a broadcastmessage or a Radio Resource Control (RRC) message (e.g., RRCReconfiguration message) to UEs. In some implementations, theconfigurations carried in the broadcast message may be updated by an RRCmessage (e.g., RRC Reconfiguration message) sent from the base station.It is noted that the system information (e.g., System Information Block1 (SIB1), other System information (SI)) may be the broadcast message.It is noted that the UE may receive the RRC message via dedicatedsignaling.

In one embodiment of the present disclosure, NR gNB/cell configures, bya configuration information, an RRC_CONNECTED UE with an SUL carrier andwith a normal uplink (non-SUL or NUL) carrier in a special cell (SpCell)or a primary cell (PCell). The SpCell may be the primary cell of amaster cell group (MCG) or the primary cell of a secondary cell group(SCG). If the multi-connectivity is not considered, the SpCell may referto a cell. If the SpCell belongs to an MCG, the configurationinformation includes an MCG configuration Information Element (e.g.,MasterCellGroup IE, MasterCellGroupConfig IE) in a form of (or a listof) Cell Group Configuration Information Element (e.g., CellGroupConfigIE, CellGroupConfigCommon IE). If the SpCell belongs to an SCG, theconfiguration information includes an SCG configuration InformationElement (e.g., SeondaryCellGroup IE, SecondaryCellGroupToAddModList IE)in a form of (or a list of) Cell Group Configuration Information Element(e.g., CellGroupConfig IE, CellGroupConfigCommon IE). The Cell GroupConfiguration Information Element (e.g., CellGroupConfig IE,CellGroupConfigCommon IE) may further include SpCell configuration(e.g., SpCellConfig IE) and/or secondary cell (SCell) configuration(e.g., SCellConfig IE). In some implementations, the NR gNB/cell maysend the MCG configuration and/or SCG configuration to the UE via an RRCmessage (e.g., RRC Reconfiguration message).

In FIG. 1, an NR wireless communication system 100 includes an NR basestation (e.g., NR gNB/cell) and a user equipment (UE) in communicativelyconnection with the NR base station. The UE may or may not operate in anRRC_CONNECTED mode. For example, the UE may operate in an RRC_IDLE,RRC_INACTIVE, or RRC_CONNECTED mode. There are at least two uplinkcarriers that are configurable for the UE, in which one of the twouplink carriers is for normal uplink (or non-supplementary uplink,non-SUL, or NUL) connection with high frequency band and small radiocoverage while the other is for supplementary uplink connection with lowfrequency band and extensive radio coverage.

If being configured with both SUL carrier and NUL carrier based on theconfiguration information by the NR gNB/cell, the UE may select anuplink carrier, based on a reference signal received power (RSRP)measured by itself in downlink (DL), to perform the random accessprocedure such as the random access preamble transmission. The UE mayperform the random access preamble transmission with random accessresources/parameters selected according to a received power of anotherDL reference signal over the selected uplink carrier. The random accessresource(s), random access parameter(s) and random accessresource(s)/parameter(s) may be used interchangeably hereinafter.

In FIG. 2, a schematic diagram is provided for an NR wirelesscommunication system according to one embodiment of the presentdisclosure. The NR wireless communication system 200 includes a UE 201and an NR gNB/cell 203. NR gNB/cell 203 sends a configurationinformation 260 to the UE 201. Configuration information 260 may be sentvia an RRC message or a system information broadcasting. Theconfiguration information 260 may include (but not limit to) the cellgroup configuration (e.g., CellGroupConfig IE, CellGroupConfigCommon IE)for the MCG configuration and/or SCG configuration. At least one of SULand NUL carrier configurations is carried in configuration information260. The SUL and NUL carrier configurations may further includeassociated random access resources/parameters. UE 201 may measure areference signal received power from NR gNB/cell 203. The UE may receivethe reference signal according to reference signal (RS) configuration.For example, the UE may receive the RS periodically according to the RSconfiguration. The UE may receive the RS configuration via a broadcastsystem information and/or an RRC message. In action 262, UE 201 mayselect an uplink carrier among the configured NUL and/or configured SULcarriers based on RSRP measurement results. In action 264, UE 201 mayfurther select random access resources/parameters in association withthe selected uplink carrier. In action 266, UE 201 may perform a randomaccess preamble transmission to NR gNB/cell 203 using the selectedrandom access resources/parameters over the selected uplink carrier. Insome implementations, if the UE is in RRC_CONNECTED mode or inRRC_INACTIVE mode, the NR gNB/cell may send an RRC message (e.g., RRCReconfiguration message, RRC Reconfiguration message with suspendconfiguration) to reconfigure the cell (e.g., SpCell, SCell).

According to one embodiment of the present disclosure, one serving cell,which may be either a primary cell or a secondary cell, can operate onan NUL carrier or an SUL carrier. In some implementations, the servingcell may be in the MCG or SCG. In FIG. 3A, it is shown that the physicaluplink control channel (PUCCH) is configured on the NUL carrier. In FIG.3B, it is shown that the PUCCH is configured on the SUL carrier. A UEmay be configured with such the serving cell on the NUL (or the SUL)carrier via the special cell configuration (e.g., SpCellConfig IE). Theserving cell may be considered in Primary Timing Advanced Group (PTAG).A Timing Advance Group containing the SpCell of a Medium Access Control(MAC) entity is referred to as PTAG. That is, cells with an ULconfigured in PTAG may use the same timing reference cell and the sameTiming Advance value. The serving cell may be a primary cell or asecondary cell. In some implementations, if the serving cell is an SCellin an MCG or in an SCG, the UE may be configured with the SCellconfiguration (e.g., SCellConfig IE). The SCell configuration maycontain serving cell configuration (e.g., ServingCellConfig IE,ServingCellConfigCommon IE, ServingCellConfigDedicated IE) for thesecondary cell. The SCell configuration may be included in the cellgroup configuration (e.g., CellGroupConfig IE, CellGroupConfigCommonIE).

When the time alignment timer (e.g., timeAlignmentTimer) associated withthe PTAG expires, the UE's MAC entity will flush all Hybrid AutomaticRepeat request (HARQ) buffers for all serving cells, notify the UE's RRCentity to release PUCCH and sounding reference signal (SRS) for allserving cells, clear any configured downlink assignments and configureduplink grants, and consider all running time alignment timers asexpired. In such situation, the NR gNB/cell cannot measure the uplinksignal quality via SRS in all serving cells.

The special cell configuration is used to configure the SpCell. Thespecial cell configuration may include synchronization reconfiguration(e.g., ReconfigurationWithSync IE). The synchronization reconfigurationmay further include serving cell configuration (e.g., ServingCellConfigIE, ServingCellConfigCommon IE, ServingCellConfigDedicated IE). Theserving cell configuration may further contain IE(s) specifying uplinkfrequency configuration. For example, the serving cell configuration maycontain the NUL carrier frequency information (e.g., FrequencylnfoULIE). For example, the serving cell configuration may contain the SULcarrier frequency information (e.g., SupplementaryUplink IE). In someimplementations, the serving cell configuration may contain the PUCCHconfiguration, physical uplink shared channel (PUSCH) configuration, SRSconfiguration, and/or timing alignment group configuration (e.g., TAGidentity (ID)).

The random access parameters may be contained in an IE corresponding tothe associated uplink carrier. In one embodiment, the common RandomAccess Channel (RACH) configuration (e.g., RACH-ConfigCommon IE,RACH-ConfigGeneric IE) may contain the contention-based random accessparameters for the SUL carrier, where the common RACH configuration iscarried in part of supplementary uplink configuration (e.g.,SupplementaryUplinkConfig IE, SupplementaryUplink IE,UplinkConfigCommonSlB IE, UplinkConfig IE). In another embodiment,common RACH configuration may contain the contention-based random accessparameters for the NUL carrier, where the common RACH configuration iscarried in part of non-supplementary uplink configuration (e.g.,non-SupplementaryUplinkConfig IE, UplinkConfig IE, FrequencyInfoUL IE,UplinkConfigCommonSIB IE). In still another embodiment, common RACHconfiguration may have an indicator to correspond the contention-basedrandom access parameters to an uplink carrier. In some implementations,the common RACH configuration is carried in part of the serving cellconfiguration.

The indicator provided in the common RACH configuration is used toindicate which type of uplink carriers the contention-based randomaccess parameters are associated with. In some implementations, aBoolean value may be assigned to the indicator in the common RACHconfiguration to tell whether the contention-based random accessparameters are for the SUL carrier or not. For example, if the indicatoris “1”, the indicator may correspond the contention-based random accessparameters to one uplink carrier (e.g., NUL). If the indicator is “0”,the indicator may correspond the contention-based random accessparameters to another uplink carrier (e.g., SUL). In someimplementations, a choice-type indicator may be used in the common RACHconfiguration to indicate if the contention-based random accessparameters are associated to the SUL, NUL or both uplink carriers. Forexample, choice {NUL, SUL, both, . . . } may define several uplinkcarriers in the choice type, to which the contention-based random accessparameters correspond. If the indicator is “NUL” from the choice type,the indicator may correspond the contention-based random accessparameters to the NUL carrier. If the indicator is “SUL”, the indicatormay correspond the contention-based random access parameters to the SULcarrier. If the indicator is “both”, the indicator may correspond thecontention-based random access parameters to both SUL and NUL carriers.The choice indicator allows the forward compatibility extension if onecell supports more than two uplink carriers.

The special cell configuration carried in part of the configurationinformation may include the synchronization reconfiguration (e.g.,ReconfigurationWithSync IE) that contains the dedicated random accessconfiguration (e.g., RACH-ConfigDedicated IE) carrying thecontention-free random access parameters. An indicator may be providedwith the dedicated random access configuration to explicitly associatesuch contention-free random access parameters with either SUL or NULcarrier. For example, a Boolean value may be assigned in the dedicatedrandom access configuration using a Boolean indicator to tell whetherthe contention-free random access parameters are for the SUL carrier ornot. For another example, a choice indicator may be used for thededicated random access configuration to indicate the contention-freerandom access parameters associated to the SUL, NUL or both uplinkcarriers. The choice indicator allows the forward compatibilityextension if one cell supports more than two uplink carriers.

The NR gNB/cell may indicate a random access preamble pool in the commonRACH configuration (e.g., RACH-ConfigCommon IE, RACH-ConfigGeneric IE)on an uplink basis. The NR gNB/cell may utilize a single common RACHconfiguration for both SUL and NUL carriers per cell. For example, ifthe single common RACH configuration is configured for an SpCell, uponreceiving the single common RACH configuration, the UE may apply theconfiguration for both SUL and NUL on the corresponding cell. The singlecommon RACH configuration may further include a list ofsub-configurations for various random access parameters. This list ofsub-configurations may not be limited to the preamble pool configurationbut include other parameters (or say, random access resources) such asthe target received preamble power (e.g., PreambleReceivedTargetPower),random access response window (e.g., RA-ResponseWindow) and maximumnumber of preamble transmission (e.g., PreambleTransMax).

A SetupRelease structure may be adopted in the serving cellconfiguration (e.g., ServingCellConfig IE, ServingCellConfigCommon IE,ServingCellConfigDedicated IE) to independently set up and/or releasethe UL carrier-specific configuration (e.g., NUL carrier configurationand SUL carrier configuration) individually. In some implementations,the SetupRelease structure may include a choice-type structure, e.g., achoice between releasing the configuration and setting up theconfiguration. For example, if the NR gNB/cell sends a SetupReleasestructure with a release choice, the UE would release the correspondingconfiguration. If the NR gNB/cell sends a SetupRelease structure with asetup choice, the UE would set up the corresponding configuration. Theconfiguration for NUL carrier (e.g., Non-supplementaryUplink IE,UplinkConfig IE, UplinkConfigCommon IE) and the configuration for SULcarrier (e.g., SupplementaryUplink IE, UplinkConfig IE,SupplementaryUplinkConfig IE, UplinkConfigCommon IE) may beindependently specified with the SetupRelease structure. NUL carrierand/or SUL carrier may be updated and/or released independently with theSetupRelease structure. In some implementations, the serving cellconfiguration may include at least one SetupRelease structures. In FIG.4, the serving cell configuration (e.g., ServingCellConfig IE) mayinclude one SetupRelease structure for NUL carrier configuration andanother SetupRelease structure for SUL carrier configurationindividually. In some implementations, the SetupRelease structure forthe SUL (or NUL) configuration may contain a threshold value associatedwith a reference signal received and measured by the UE, e.g., an RSRPthreshold value. The value for RSRP threshold (RSRP threshold value) maybe put in an independent field in the SetupRelease structure (e.g., anSUL configuration with a SetupRelease structure, an NUL configurationwith a SetupRelease structure) in the serving cell configuration. Insome implementations, the RSRP threshold value may be put in a field ofthe uplink frequency information configuration (e.g., FrequencylnfoULIE, FrequencylnfoUL-SIB IE). The UL carrier configuration with aSetupRelease structure may include the uplink frequency informationconfiguration. The RSRP threshold value may be set to positive infinity,negative infinity or zero. If the RSRP threshold value is set to zero,the unit of the value may not be dBm but Watt (W). In someimplementations, the UE may receive the RSRP threshold value via systeminformation (e.g., SIB1, other SI) broadcast by the NR gNB/cell or viaRRC message (e.g., RRC Reconfiguration message) transmitted by the NRgNB/cell.

When the UE selects the UL carrier based on the RSRP threshold, the UEmay select the SUL carrier if the RSRP threshold value is set topositive infinity; the UE may select the NUL (non-SUL) carrier if theRSRP threshold is set to zero or negative infinity.

Instead of the SetupRelease structure, a choice structure between setupand release may be used to indicate uplink carrier-specificconfigurations. In FIG. 5, an exemplary choice structure is illustrated.

In some implementations, if the cell (e.g., SpCell, SCell) is configuredwith both SUL carrier and NUL carrier, the UE may select which uplinkcarrier to perform Random Access Preamble transmission based on themeasured RSRP of the downlink carrier and/or based on the types ofrandom access resources/parameters (e.g., contention-based and/orcontention-free) configured to the SUL carrier and/or NUL carrier.

After receiving the configuration information, the UE may select anuplink carrier based on the uplink carrier configuration. FIG. 6schematically illustrates a decision flow chart for an RRC_CONNECTED UEto select an uplink carrier and corresponding random access resourcesaccording to one embodiment of the present disclosure. It is noted thatthe decision flow chart in FIG. 6 may be applied to an RRC_INACTIVE UEor an RRC_IDLE UE. The decision flow chart of FIG. 6 may be applied to,but not limited to, a situation when an uplink transmission is neededafter time alignment timer(s) expires. At action S61, the UE maydetermine if a downlink RSRP is below (or equal to) the RSRP thresholdvalue given in a corresponding configuration (e.g., ServingCellConfigIE). The UE may select the SUL carrier (if configured) if an RSRPmeasured in downlink is below (or equal to) the RSRP threshold valuegiven in the corresponding configuration. The UE may select the randomaccess resources/parameters on the selected SUL carrier in the cell(e.g., SpCell, SCell). If both contention-based and contention-freerandom access resources/parameters are configured in association withthe SUL carrier, the UE may further judge whether the uplink traffic isfor specific access requests (e.g., emergency call, specific accesscategory or Ultra-Reliable and Low Latency Communications (URLLC)traffic) at action S62 and action S63. If the uplink traffic isdetermined for a specific access request, the UE may perform the randomaccess preamble transmission based on the contention-free random accessresources/parameters over the selected SUL carrier at action S64; if theuplink traffic is determined not for a specific access request, the UEmay perform the random access preamble transmission based on thecontention-based random access resources/parameters over the selectedSUL carrier at action S65. In some implementations, if one of thecontention-based and contention-free random access parameters isconfigured specifically for the SUL carrier, the UE may perform therandom access preamble transmission based on the random accessresources/parameters configured specifically for the SUL carrier withoutchecking the uplink traffic type on the condition that the RSRP of NR DLsignal is less than (or equal to) the RSRP threshold.

At action S63, the UE may select the NUL carrier if the measured RSRP isabove the RSRP threshold value. At actions S66 and S67, the UE mayselect the random access resources/parameters on the selected NULcarrier in the cell (e.g., SpCell, SCell). If both contention-based andcontention-free random access resources/parameters are configured inassociation with the NUL carrier, the UE may further judge whether theuplink traffic is for specific access requests (e.g., emergency call,specific access category or URLLC traffic) at action S66 and action S67.If the uplink traffic is determined for a specific access request, theUE may perform the random access preamble transmission based on thecontention-free random access resources/parameters over the selected NULcarrier at action S66; if the uplink traffic is determined not for aspecific access request, the UE may perform the random access preambletransmission based on the contention-based random accessresources/parameters over the NUL carrier at action S67. In someimplementations, if one of the contention-based and contention-freerandom access parameters is configured specifically for the NUL carrier,the UE may perform the random access preamble transmission based on therandom access resources/parameters configured specifically for the NULcarrier without checking the uplink traffic type on the condition thatthe RSRP of NR DL signal is above the RSRP threshold.

After receiving the configuration information, the UE may select anuplink carrier based on the uplink carrier configuration. FIG. 7schematically illustrates a decision flow chart for an RRC_CONNECTED UEto select an uplink carrier and corresponding random access resourcesaccording to another embodiment of the present disclosure. It is notedthat the decision flow chart in FIG. 7 may be applied to an RRC_INACTIVEUE or an RRC_IDLE UE. In FIG. 7, the UE may select random accessresources/parameters based on uplink traffic types and a measured RSRP.The decision flow chart of FIG. 7 may be applied to, but not limited to,a situation when an uplink transmission is needed after time alignmenttimer(s) expires. At action S71, the UE may judge whether the uplinktraffic is for specific access requests (e.g., emergency call, specificaccess category or URLLC traffic). If the uplink traffic is determinedfor a specific access request, the UE may further determine whether themeasured DL RSRP value is below (or equal to) the RSRP threshold valuegiven in the corresponding configuration at action S72; if the uplinktraffic is determined not for a specific access request, the UE mayperform the random access preamble transmission based oncontention-based random access resources/parameters over an SUL carrierin the cell (e.g., SpCell, SCell) at action S73. If the DL RSRP ismeasured to be below (or equal to) the RSRP threshold value after actionS72, the UE may select an SUL carrier to perform the random accesspreamble transmission based on the contention-free random accessresources/parameters associated with the selected SUL carrier at actionS74; if the DL RSRP is measured to be above the RSRP threshold valueafter action S72, the UE may perform the random access preambletransmission based on the contention-free random accessresources/parameters over the NUL carrier in the cell (e.g., SpCell,SCell) at action S75. In some implementations, if the UE are notconfigured with the contention-free random access resources/parametersof the SUL carrier in the cell (e.g., SpCell, SCell), the UE may performthe random access preamble transmission based on contention-based randomaccess resources/parameters over an SUL carrier in the cell if theuplink traffic is determined for a specific access request and themeasured DL RSRP value is below (or equal to) the RSRP threshold valuegiven in the corresponding configuration. In some implementations, ifthe UE are not configured with the contention-free random accessparameters of the NUL carrier in the cell (e.g., SpCell, SCell), the UEmay (1) perform the random access preamble transmission based on thecontention-based random access resources/parameters over the NUL carrierin the cell, or (2) perform the random access preamble transmissionbased on the contention-free random access resources/parameters over anSUL carrier in the cell, or (3) perform the random access preambletransmission based on the contention-based random accessresources/parameters over an SUL carrier in the cell, when the uplinktraffic is determined for a specific access request and the measured DLRSRP value is above an RSRP threshold value. In some implementations,the UE may select among the three approaches (1)(2)(3) following thepriority (e.g., approach (1) has the highest priority, approach (3) hasthe lowest priority). The priority may be indicated by the NR gNB/cellvia system information or via an RRC message (e.g., RRC Reconfigurationmessage). The priority may be UE's implementation.

In some other embodiments, the UE may be further configured with anotherRSRP threshold value to determine which of contention-based randomaccess procedure and contention-free random access procedure should beperformed. If the UE measures a DL RSRP to be higher than the anotherRSRP threshold value, the UE may select contention-free random accessresources/parameters to perform contention-free random access procedurewith the contention-free random access resources having been configuredin either UL carrier (e.g., SUL or NUL carriers). If the measured DLRSRP is less than (or equal to) another RSRP threshold value, the UE mayperform the contention-based random access procedure with thecontention-based random access resources having been configured ineither UL carrier (e.g., SUL or NUL carriers). If another RSRP thresholdvalue is set to positive infinity, the UE may perform thecontention-based random access procedure. If another RSRP thresholdvalue is set to zero, the UE may perform the contention-free randomaccess procedure. If another RSRP threshold value is set to negativeinfinity, the UE may perform the contention-free random accessprocedure. It is noted that this threshold value for determining thetype of random access procedure may or may not be identical to the RSRPthreshold value on which the selection of an uplink carrier is based.

It is noted that the random access resources (in the contention-basedrandom access procedure and/or the contention-free random accessprocedure) may be selected in association to the signal quality of theSS (Synchronization Signal) blocks and/or CSI-RS (Channel StateInformation Reference Signal) resources. The UE may select thecontention-free random access resources if either SS block or CSI-RSmeasured by itself is above a corresponding RSRP threshold value.Whether the random access procedure is successful may depend on thesignal quality of SS blocks and/or CSI-RS.

In some embodiments, if the two RSRP thresholds both are configured tothe UE, the UE may compare the measured DL RSRP (e.g., SS blocks,CSI-RS) to these two thresholds to select a corresponding random accessprocedure (e.g., contention-based random access procedure,contention-free random access procedure) on the selected UL carrier ifthe random access procedure fails.

In some embodiments of the present disclosure, the random accessprocedure may fail. There are several reasons causing the random accessprocedure to fail. For example, the maximum preamble (re)transmissiontimes are achieved; the signal quality of Physical Random Access Channel(PRACH) resources is below a threshold; the associated physicalresources to the PRACH resources has poor signal quality; the time spenton the random access procedure exceeds a given timer.

In some implementations, if the random access procedure fails in one ULcarrier, the UE may switch to another UL carrier to perform the randomaccess procedure. In some implementations, the UE may continuetimer(s)/counter(s) calculated in the failed random access procedure,e.g., the existing parameters are not reset. In some implementations,the UE may abort the timer(s)/counter(s) calculated in the failed randomaccess procedure, and begin a new random access procedure. For example,if the UE is configured with both non-SUL carrier and SUL carrier andthe corresponding random access resources/parameters on each UL carrier,the UE may by default first perform the random access procedure on theSUL carrier. If at least one random access procedure (e.g., a randomaccess procedure following contention-based random accessresources/parameters, a random access procedure followingcontention-free random access resources/parameters) fails on the SULcarrier, the UE may switch to the non-SUL carrier to perform the randomaccess procedure.

In some implementations, if one UL carrier is configured withcontention-based random access resources/parameters and the other ULcarrier is configured with contention-free random accessresources/parameters, the UE may first select the UL carrier which isconfigured with contention-free random access resources/parameters. TheUE may select the UL carrier based on the types of random accessresources/parameters.

In some implementations, if the contention-free random access procedurefails in either SUL carrier or non-SUL carrier, the UE may perform thecontention-based random access procedure (if the contention-based randomaccess resources/parameters are configured) on the same UL carrier.

In some implementations, if the contention-free random access procedurefails in either SUL carrier or non-SUL carrier, the UE may perform therandom access procedure on the other UL carrier. If both contention-freeand contention-based random access resources/parameters are configuredon the other UL carrier, the UE may perform the contention-free randomaccess procedure on the other UL carrier as the high priority. Forexample, the UE may perform the contention-free random access procedureon the other UL carrier rather than the contention-based random accessprocedure. For example, the UE may perform the contention-free randomaccess procedure on the other UL carrier with a higher probability thanthe contention-based random access procedure on the other UL carrier.

If the received signal of the random access response on one UL carrieris below a threshold, the UE can switch to perform the random accessprocedure on the other UL carrier. The NR gNB/cell may configure thethreshold to the UE via system information (e.g., SIB1, other SI) or viaan RRC message (e.g., RRC Reconfiguration message).

It is noted that the embodiments mentioned in the present disclosure maynot be limited to the RRC_CONNECTED UE. These embodiments may be appliedfor the RRC_INACTIVE UE and/or RRC_IDLE UE. For example, the selectionamong random access resources/parameters and UL carriers based on thetype of access requests may also be applied for the RRC_IDLE UE and/orRRC_INACTIVE UE. For example, the selection among random accessresources/parameters and UL carriers based on the measured DL RSRP mayalso be applied for the RRC_IDLE UE and/or RRC_INACTIVE UE.

If there is no other contention-based and/or contention-free randomaccess resources/parameters on the UL carriers associated to the same DLcarrier, the UE may enter to the RRC_IDLE mode (e.g., if the security isnot activated), or RRC_INACTIVE mode, or perform the RRCconnection-reestablishment procedure (e.g., if the security isactivated).

It is noted that the embodiments mentioned above in the presentdisclosure may not be limited to the conditions when the time alignmenttimer expires. For example, other triggering cases to perform randomaccess preamble transmission may be applied.

It is noted that the configuring of contention-free and/orcontention-based random access resources/parameters on the SUL or NULcarrier may also be performed via the NR gNB/cell's broadcast messages,for example, SIB1, remaining system information (RMSI), other SI and ondemand SI.

It is noted that in the present disclosure, the value of RSRP thresholdcan be set to zero or (positive or negative) infinity. If it is zero,the RSRP threshold value may be configured in unit of Watt (W) ormilliWatt (mW). In some implementations, the RSRP threshold(s) may beincluded in the common RACH configuration (e.g., RACH-ConfigCommon IE).In some implementations, the RSRP threshold value may range from zero toa defined number (or to infinity). In some implementations, the RSRPthreshold value may range from negative infinity to positive infinity.

In some embodiments, the NR gNB may send the configuration informationto the UE for (re)configuring the cell (e.g., SpCell, SCell) with SULand NUL carriers simultaneously via a single RRC message (e.g., RRCReconfiguration message, RRCConnectionReconfiguration message) orsequentially via separate RRC messages (e.g., RRC Reconfigurationmessage, RRCConnectionReconfiguration message).

A. Simultaneous SUL and NUL Configuration

If the RRC_CONNECTED UE is configured with both SUL and NUL carriers bythe NR gNB/cell via an RRC message (e.g., RRC Reconfiguration message)simultaneously, the supplementary uplink configuration (e.g.,SupplementaryUplink IE, UplinkConfig IE, SupplementaryUplinkConfig IE,UplinkConfigCommonSIB IE) and non-supplementary uplink configuration(e.g., non-SupplementaryUplinkConfig IE, FrequencyInfoUL IE,UplinkConfig IE, UplinkConfigCommon IE) may both have valid informationto configure the cell (e.g., SpCell, SCell). In some implementations,the common RACH configuration includes random accessresources/parameters, for different uplink carriers. For example, onlyone uplink carrier (either SUL or NUL carrier) is configured inassociation with contention-based random access parameters; all uplinkcarriers are configured, respectively, in association with separatecontention-based random access parameters; only one uplink carrier(either SUL or NUL carrier) is configured in association withcontention-free random access parameters; all uplink carriers areconfigured, respectively, in association with separate contention-freerandom access parameters.

B. Sequential SUL and NUL Configuration

If the NR gNB configures the UE with SUL and NUL carriers sequentiallyvia separate RRC messages (e.g., RRC Reconfiguration message) orseparate system information (SI), each RRC message (e.g., RRCReconfiguration message)/SI may contain one or more uplink carrierconfiguration and the associated contention-based and/or contention-freerandom access resources/parameters. Note that the SI may be broadcast ortransmitted via dedicated signaling.

In one embodiment, the UE may not update or remove currently existinguplink carrier configuration and the associated random access parameters(contention-based and/or contention-free) when receiving theconfiguration information that contains null uplink carrierconfiguration IE (e.g., a null value assigned in the supplementaryuplink configuration, a null value assigned in the non-supplementaryuplink configuration).

In one embodiment, the UE may update or remove currently existing uplinkcarrier configuration and the associated random access parameters(contention-based and/or contention-free) when receiving theconfiguration information that contains null uplink carrierconfiguration IE (e.g., a null value assigned in the supplementaryuplink configuration, a null value assigned in the non-supplementaryuplink configuration).

In one embodiment, the UE may update or remove currently existing uplinkcarrier configuration and the associated random access parameters(contention-based and/or contention-free) when receiving theconfiguration information that contains a removal indicator carried inpart of the uplink carrier configuration (e.g., in the supplementaryuplink configuration, in the non-supplementary uplink configuration, inthe contention-based random access parameters, in the contention-freerandom access parameters, in the common RACH configuration, in thededicated random access configuration).

In one embodiment of the present disclosure, the NR gNB/cell may sendthe configuration information to configure RRC_CONNECTED UE with the SULcarrier only in the cell (e.g., SpCell, SCell).

In some implementations, the supplementary uplink configuration (e.g.,SupplementaryUplink IE, UplinkConfig IE, SupplementaryUplinkConfig IE,UplinkConfigCommonSIB IE) may contain contention-based random accessparameters associated with the SUL carrier. For example, thesupplementary uplink configuration may include the common RACHconfiguration (e.g., RACH-ConfigCommon IE) specifically corresponding torandom access parameters over the SUL carrier. Since the cell (e.g.,SpCell, SCell) may not be configured with normal uplink (non-SUL or NUL)carrier, the serving cell configuration (e.g., ServingCellConfig IE,ServingCellConfigCommon IE, ServingCellConfigDedicated IE) may notinclude the NUL configuration (e.g., frequency information for the NULcarrier).

In some implementations, a Boolean value may be assigned in thesupplementary uplink configuration using a Boolean indicator (e.g.,RachCommonUsage) to inform the UE of the association between the SULcarrier and the random access parameters (e.g., contention-based randomaccess parameters, contention-free random access parameters, common RACHconfiguration, dedicated random access configuration). In someimplementations, the NR gNB/cell may configure the NUL carrier to the UEvia the serving cell configuration. The serving cell configuration maycomprise the random access parameters. In some implementations, oneBoolean indicator may be required in the supplementary uplinkconfiguration to associate the random access parameters with the SULcarrier. For example, if the Boolean indicator is “1”, the random accessparameters may be associated with the SUL carrier. If the Booleanindicator is “0”, the random access parameters may not be associatedwith the SUL carrier. If the Boolean indicator is “0”, the random accessparameters may be associated with another uplink carrier (e.g., NULcarrier). In some implementations, a Boolean value may be assigned inthe non-supplementary uplink configuration (e.g., non-SupplementaryUplinkConfig IE, UplinkConfig IE, FrequencylnfoUL IE,UplinkConfig IE) using a Boolean indicator (e.g., RachCommonUsage) toinform the UE of the association between the NUL carrier and the randomaccess parameters (e.g., contention-based random access parameters,contention-free random access parameters, common RACH configuration,dedicated random access configuration). In some implementations, the NRgNB/cell may configure the SUL carrier to the UE via the serving cellconfiguration. The serving cell configuration may comprise the randomaccess parameters. In some implementations, one Boolean indicator may berequired in the non-supplementary uplink configuration to associate therandom access parameters with the NUL carrier. For example, if theBoolean indicator is “1”, the random access parameters may be associatedwith the NUL carrier. If the Boolean indicator is “0”, the random accessparameters may not be associated with the NUL carrier. If the Booleanindicator is “0”, the random access parameters may be associated withanother uplink carrier (e.g., SUL carrier).

In some implementations, if the configuration for NUL carrier (e.g.,FrequencylnfoUL IE, UplinkConfig IE, UplinkConfigCommon IE) is notpresent and only that for the SUL carrier (e.g., FrequencyInfoUL IE,SupplementaryUplink IE, SupplementaryUplinkConfig IE, UplinkConfig IE,UplinkConfigCommonSIB IE) is present in the serving cell configuration,the common RACH configuration specifically corresponding tocontention-based random access parameters may be considered toimplicitly associate with the SUL carrier. The common RACH configurationmay be included in the serving cell configuration. In someimplementations, if the configuration for NUL carrier is not present andonly that for the SUL carrier is present in the serving cellconfiguration, the dedicated random access configuration (e.g.,RACH-ConfigDedicated IE) specifically corresponding to contention-freerandom access parameters may be considered to implicitly associate withthe SUL carrier. The dedicated random access configuration may beincluded in the serving cell configuration. In some implementations, ifthe configuration for SUL carrier is not present and only that for theNUL carrier is present in the serving cell configuration, the commonRACH configuration specifically corresponding to contention-based randomaccess parameters may be considered to implicitly associate with the NULcarrier. The common RACH configuration may be included in the servingcell configuration. In some implementations, if the configuration forSUL carrier is not present and only that for the NUL carrier is presentin the serving cell configuration, the dedicated random accessconfiguration specifically corresponding to contention-free randomaccess parameters may be considered to implicitly associate with the NULcarrier. The dedicated random access configuration may be included inthe serving cell configuration.

In some implementations, a choice indicator may be included in thecommon RACH configuration to indicate the contention-based random accessparameters associated to the SUL, NUL or both uplink carriers. In someimplementations, a choice indicator may be included in the dedicatedrandom access configuration to indicate the contention-free randomaccess parameters associated to the SUL, NUL or both uplink carriers.The choice indicator allows the forward compatibility extension if onecell supports more than two uplink carriers. In some implementations, aBoolean indicator may be included in the common RACH configuration toindicate whether the contention-based random access parameters areassociated to a specific uplink carrier. For example, if the Booleanindicator is “1”, the UE may apply the common RACH configuration for theSUL carrier. If the Boolean indicator is “0”, the UE may apply thecommon RACH configuration for the NUL carrier. In some implementations,a Boolean indicator may be included in the dedicated random accessconfiguration to indicate whether the contention-free random accessparameters are associated to a specific uplink carrier. For example, ifthe Boolean indicator is “1”, the UE may apply the dedicated randomaccess configuration for the SUL carrier. If the Boolean indicator is“0”, the UE may apply the dedicated random access configuration for theNUL carrier. It is noted that the common RACH configuration includingthe indicator (e.g., choice indicator, Boolean indicator) may not becarried in the uplink carrier configuration such as the supplementaryuplink configuration for SUL carrier and/or the normal uplinkconfiguration for NUL carrier. It is noted that the dedicated randomaccess configuration including the indicator (e.g., choice indicator,Boolean indicator) may not be carried in the uplink carrierconfiguration such as the supplementary uplink configuration for SULcarrier and/or the normal uplink configuration for NUL carrier.

In one embodiment, the NR gNB/cell may send a configuration informationvia an RRC message (e.g., RRC Reconfiguration message) to configure theRRC_CONNECTED UE with contention-free random access parameters specificto the SUL. The special cell configuration carried in the configurationinformation may include the synchronization reconfiguration thatcontains the dedicated random access configuration carrying thecontention-free random access parameters. An indicator may be providedwith the dedicated random access configuration to explicitly associatesuch contention-free random access parameters with either SUL or NULcarrier. For example, a Boolean indicator or a choice indicator may beapplied to this case.

In some implementations, the UE may by default adopt thecontention-based random access configuration on the SUL carrier.However, if the NR gNB/cell only configures the contention-free randomaccess configuration on the SUL carrier, the UE may perform thecontention-free random access procedure. If the NR gNB/cell configuresboth the contention-free random access parameters and contention-basedrandom access parameters on the SUL carrier, the UE may select whichrandom access parameters to follow based on the uplink traffic types. Ifthe NR gNB/cell configures both the contention-free random accessparameters and contention-based random access parameters on the SULcarrier, the UE may select which random access parameters to followbased on the RSRP threshold value. For example, the measured DL RSRP(e.g., SS blocks, CSI-RS) associated to the random access resources ishigher than an RSRP threshold value, the UE may select thecontention-free random access parameters on the SUL carrier.

In one embodiment of the present disclosure, the NR gNB/cell may sendthe configuration information to configure RRC_CONNECTED UE with thenon-SUL carrier only in the cell (e.g., SpCell, SCell).

In some implementations, special cell configuration may carry thesynchronization reconfiguration which contains the non-supplementaryuplink configuration. The non-supplementary uplink configuration mayhave the frequency information for the non-SUL carrier. If otherinformation is required for the non-SUL carrier, a new configuration maybe required (e.g., Non-supplementaryUplink IE, UplinkConfigCommon IE,UplinkConfig IE) to include the frequency information for the non-SULcarrier and other information such as the random access informationcorresponding to such non-SUL carrier.

The supplementary uplink configuration in the special cell configurationmay or may not be present. If the SpCell is configured with non-SULcarrier only, even though the supplementary uplink configuration ispresent, the value in the supplementary uplink configuration may benull. That is, the supplementary uplink configuration (e.g.,SupplementaryUplink IE, SupplementaryUplinkConfig IE, UplinkConfig IE,UplinkConfigCommonSIB IE) is empty.

The non-SUL configuration may contain the common RACH configurationincluding contention-based random access parameters specifically to thenon-SUL carrier. In some implementations, if the cell is not configuredwith SUL carrier, the serving cell configuration may not include thefrequency information for SUL carrier. For example, the serving cellconfiguration may not include the supplementary uplink configuration.

An indicator (e.g., Boolean indicator or choice indicator) may be usedin the common RACH configuration.

In some implementations, the UE may by default adopt thecontention-based random access configuration on the non-SUL carrier.However, if the NR gNB/cell only configures the contention-free randomaccess configuration on the non-SUL carrier, the UE may perform thecontention-free random access procedure. If the NR gNB/cell configuresboth the contention-free random access parameters and contention-basedrandom access parameters on the non-SUL carrier, the UE may select whichrandom access parameters to follow based on the uplink traffic types. Ifthe NR gNB/cell configures both the contention-free random accessparameters and contention-based random access parameters on the non-SULcarrier, the UE can select which random access parameters to followbased on the RSRP threshold value. For example, the measured DL RSRP(e.g., SS blocks, CSI-RS) associated to the random access resources ishigher than an RSRP threshold value, the UE may select thecontention-free random access parameters on the non-SUL carrier.

FIG. 8 illustrates a block diagram of a device for wirelesscommunication, according to various exemplary embodiments of the presentdisclosure. As shown in FIG. 8, device 800 may include transceiver 820,processor 826, memory 828, one or more presentation components 834, andat least one antenna 836. Device 800 may also include an RF spectrumband module, a base station communications module, a networkcommunications module, and a system communications management module,input/output (I/O) ports, I/O components, and power supply (notexplicitly shown in FIG. 8). Each of these components may be incommunication with each other, directly or indirectly, over one or morebuses 826.

Transceiver 820 having transmitter 822 and receiver 824 may beconfigured to transmit and/or receive time and/or frequency resourcepartitioning information. In some embodiments, transceiver 820 may beconfigured to transmit in different types of subframes and slotsincluding, but not limited to, usable, non-usable and flexibly usablesubframes and slot formats. Transceiver 820 may be configured to receivedata and control channels.

Device 800 may include a variety of computer-readable media.Computer-readable media can be any available media that can be accessedby device 800 and include both volatile and non-volatile media,removable and non-removable media. By way of example, and notlimitation, computer-readable media may comprise computer storage mediaand communication media. Computer storage media may include bothvolatile and non-volatile, removable and non-removable media implementedin any method or technology for storage of information such ascomputer-readable instructions, data structures, program modules orother data.

Computer storage media includes Random Access Memory (RAM), Read-OnlyMemory (ROM), Electrically-Erasable Programmable Read-Only Memory(EEPROM), flash memory or other memory technology, Compact DiscRead-Only Memory (CD-ROM), digital versatile disks (DVD) or otheroptical disk storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices. Computer storage media doesnot comprise a propagated data signal. Communication media typically mayembody computer-readable instructions, data structures, program modulesor other data in a modulated data signal such as a carrier wave or othertransport mechanism and includes any information delivery media. Theterm “modulated data signal” may mean a signal that has one or more ofits characteristics set or changed in such a manner as to encodeinformation in the signal. By way of example, and not limitation,communication media may include wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared and other wireless media. Combinations of any of the aboveshould also be included within the scope of computer-readable media.

Memory 828 may include computer-storage media in the form of volatileand/or non-volatile memory. Memory 828 may be removable, non-removable,or a combination thereof. Exemplary memory may include solid-statememory, hard drives, optical-disc drives, etc. As illustrated in FIG. 8,memory 828 may store computer-readable, computer-executable instructions832 (e.g., software codes) that are configured to, when executed, causeprocessor 826 to perform various functions described herein, forexample, with reference to FIGS. 1 through 7. Alternatively,computer-readable instructions 832 may not be directly executable byprocessor 826 but be configured to cause device 800 (e.g., when compiledand executed) to perform various functions described herein.

Processor 826 may include an intelligent hardware device, e.g., acentral processing unit (CPU), a microcontroller, an ApplicationSpecific Integrated Circuit (ASIC), etc. Processor 826 may includememory. Processor 826 may process data 830 and computer-executableinstructions 832 received from memory 828, and information throughtransceiver 820, the base band communications module, and/or the networkcommunications module. Processor 826 may also process information to besent to transceiver 820 for transmission through antenna 836, to thenetwork communications module for transmission to a core network.

One or more presentation components 834 may present data indications toa person or other device. Exemplary one or more presentation components834 may include a display device, speaker, printing component, vibratingcomponent, etc.

From the above description it is manifest that various techniques can beused for implementing the concepts described in the present disclosurewithout departing from the scope of those concepts. Moreover, while theconcepts have been described with specific reference to certainembodiments, a person of ordinary skill in the art would recognize thatchanges can be made in form and detail without departing from the scopeof those concepts. As such, the described embodiments are to beconsidered in all respects as illustrative and not restrictive. Itshould also be understood that the present disclosure is not limited tothe particular embodiments described above, but many rearrangements,modifications, and substitutions are possible without departing from thescope of the present disclosure.

What is claimed is:
 1. A user equipment (UE) for wireless communication,comprising: one or more non-transitory computer-readable media havingexecutable instructions embodied thereon; and at least one processorcoupled to the one or more non-transitory computer-readable media andconfigured to execute the executable instructions to: receiveconfiguration information associated with at least two uplink carriers;select one of the at least two uplink carriers if power of a firstdownlink reference signal measured by the UE is below a first thresholdvalue; select a contention-free random access (CFRA) resource associatedwith a second downlink reference signal on the selected uplink carrierif power of the second downlink reference signal measured by the UE isabove a second threshold value, wherein the second downlink referencesignal is synchronization signal block (SSB) or channel stateinformation reference signal (CSI-RS), and the second threshold value isassociated with signal quality of the SSB and the CFRA resource isassociated with the SSB if the second downlink reference signal is theSSB; and wherein the second threshold value is associated with signalquality of the CSI-RS and the CFRA resource is associated with CSI-RS ifthe second downlink reference signal is the CSI-RS; and perform a randomaccess procedure using the selected CFRA resource and the selecteduplink carrier.
 2. The UE of claim 1, wherein the first threshold valueis carried in part of the configuration information.
 3. The UE of claim2, wherein the part of the configuration information that carries thefirst threshold value is structured with a SetupRelease structure. 4.The UE of claim 1, wherein the configuration information is received viasystem information broadcasting or dedicated signaling.
 5. The UE ofclaim 4, wherein the at least one processor is further configured toexecute the executable instructions to: remove existing uplink carrierconfiguration when receiving, via the system information broadcasting,the configuration information with a null value.
 6. The UE of claim 4,wherein frequency information for the selected uplink carrier is carriedin synchronization reconfiguration sent by the dedicated signaling. 7.The UE of claim 1, wherein the at least one processor is furtherconfigured to execute the executable instructions to: select acontention-based random access (CBRA) resource on the selected uplinkcarrier if the random access procedure using the selected CFRA resourcefails.
 8. The UE of claim 1, wherein the CFRA resource is configured inprimary cell configuration information element carried in a RadioResource Control (RRC) message.
 9. A method for wireless communication,comprising: receiving, by a user equipment (UE), configurationinformation associated with at least two uplink carriers; selecting, bythe UE, one of the at least two uplink carriers if power of a firstdownlink reference signal measured by the UE is below a first thresholdvalue; selecting, by the UE, a contention-free random access (CFRA)resource associated with a second downlink reference signal on theselected uplink carrier if power of the second downlink reference signalmeasured by the UE is above a second threshold value, wherein the seconddownlink reference signal is synchronization signal block (SSB) orchannel state information reference signal (CSI-RS), and the secondthreshold value is associated with signal quality of the SSB and theCFRA resource is associated with the SSB if the second downlinkreference signal is the SSB; and wherein the second threshold value isassociated with signal quality of the CSI-RS and the CFRA resource isassociated with CSI-RS if the second downlink reference signal is theCSI-RS; and performing, by the UE, a random access procedure using theselected CFRA resource and the selected uplink carrier.
 10. The methodof claim 9, wherein the first threshold value is carried in part of theconfiguration information.
 11. The method of claim 10, wherein the partof the configuration information that carries the first threshold valueis structured with a SetupRelease structure.
 12. The method of claim 9,wherein the configuration is received via system informationbroadcasting or dedicated signaling.
 13. The method of claim 12, furthercomprising: removing existing uplink carrier configuration whenreceiving, via the system information broadcasting, the configurationinformation.
 14. The method of claim 12, wherein frequency informationfor the selected uplink carrier is carried in synchronizationreconfiguration sent by the dedicated signaling.
 15. The method of claim9, further comprising: selecting a contention-based random access (CBRA)resource on the selected uplink carrier if the random access procedureusing the selected CFRA resource fails.
 16. The method of claim 9,wherein the CFRA resource is configured in primary cell configurationinformation element carried in a Radio Resource Control (RRC) message.